1. Field of the Invention
The present invention relates to Internet coupled audio communications. More specifically, the present invention relates to an apparatus and method for scanning streaming Internet audio feeds and broadcast radio signals for the reception of active audio signals within intermittent audio content.
2. Description of the Related Art
Scanning radio receivers, commonly known as “police scanners” or simply “scanners”, allow users to listen to police, fire, aircraft, marine, business and other manner of one-way and two-way radio communications across a broad spectrum of frequencies, typically ranging from 25 MHz to 1300 MHz. Most scanners have a channel memory that is used to store one or more receiver frequencies, or indicia of frequency, that can be recalled by referencing a channel number, thereby simplifying the entry of desired reception frequencies. Various types of scanners are known, some operating in a few bands of frequencies with limited channel memory capacity, others being full-featured models that cover all the available bands and including generous channel memory capacity. Scanners are enabled to sequentially change channels, thereby scanning through a list of frequencies, searching for broadcasts comprised of intermittent audio content that may be of interest to a listener. Scanners are able to receive local radio broadcasts, with the range limited by transmitter power and receiver sensitivity. Typically maximum listening ranges are approximately twenty-five to forty miles.
Scanner radio receivers employ some form of squelch control so that noise and undesirable communications are not routed through to a loudspeaker or earphone. Carrier squelch can be used, which gates received audio to a loudspeaker based on the signal-to-noise ratio or carrier-to-noise ratio of the receiver discriminator output. Other systems employ out of band tones that are detected to control a squelch gate. One such system employs plural sub-audible tones, and is referred to as a continuously tone coded squelch system (“CTCSS”). The receiver channel includes the frequency of the CTCSS tone, and checks for that particular one of the plural tones based on the channel programming, and detection of a matching tone enables the squelch gate of the receiver. The tones are stored in the channel memory, linked to the corresponding frequency of reception. Thus, when a channel is selected for reception, the scanner recalls both the frequency of reception and the squelch tone. Another squelch system employs digital data fields that are broadcast along with the radio signals, and the receiver looks for a matching digital code. Such systems are referred to as digitally coded squelch systems (“DCS”). Other squelch control systems are known as well. In general, the squelch gate couples audio from the receiver discriminator to an audio output circuit, which may include a loudspeaker, earphone, recorder, or other output device.
Early two-way radio systems employed a single radio frequency or a duplex pair of radio frequencies for two-way communications. Such systems lent themselves well to scanner receiver monitoring because a given two-way radio fleet of users, such as the local police department, could be readily monitored by receiving a single, predetermined, radio frequency. However, heavy radio use demand and congested airways caused manufacturers to develop more efficient radio systems. One solution was the trunked radio system where a group of two to twenty-eight duplex pairs of radio frequencies are allocated together for shared use by plural fleets of users. In a trunked system, talk group identities are assigned to the fleets, which are used to provide receiver squelch gate control for the plural members of the fleet. The difference in a trunked radio system vis-á-vis a conventional system is that the radio frequencies are dynamically allocated during use. As such, a conversation between a dispatcher and a fleet of patrol cars, for example, can change from frequency to frequency within the trunked group of frequencies during the course of a conversation. Suppliers of scanning receivers addressed this difference in functionality by developing radios that could track the talk group identities (“Talk group ID's”) and dynamically hop from frequency to frequency as the conversation progressed. The key to radio scanner operation in a trunking environment is to have all of the trunking frequencies for each trunk group stored in the scanner channel memory, typically associated with a system identity (“System ID”), and then track the talk group ID code of the desired fleet, along with the dynamic allocation of the trunking frequencies. In this way, the trunked scanner functions like a conventional scanner from the user's perspective, with the “channel” actually associated with both a trunking system ID and a talk group ID instead of the conventional radio system frequency-to-channel, plus squelch code, correlation.
Scanning enthusiasts frequently look for “the action” in public safety radio systems. These kinds of events include major fires, police chases, airplane crashes and other breaking news kinds of events. One problem is that breaking news events happen at distant locations, which are out of the range of the scanner's operating environment. The Internet has been used to increase the useful range of scanner operation. Enthusiasts are now enabled to connect the audio output of the scanner to an Internet streaming audio server computer, and thereby allow other enthusiasts to access the received scanner audio signals over an Internet connection. For example, an Internet connected scanner in Chicago may receive a breaking news car chase, while an enthusiasts in Boston listens to the action on their computer loudspeakers by addressing the streaming audio server in Chicago. In fact, there are hundreds, perhaps thousands of Internet scanner feeds active at any given time, with more becoming active all the time. The challenge to enthusiasts is to find “the action” on the Internet scanner feeds. While scanning enthusiasts are familiar with channel scanning operations in their radio scanners, which enables them to quickly find “the action” in their local region, enthusiasts are frustrated in finding “the action” when surfing Internet scanner feeds. Thus, there is a need in the art for an apparatus and method for providing scanning radio receiver functionality to Internet based scanner feeds.